Dear 100 Hour Board,
What percentage of the land on earth has a land-based antipode? That is, for how much of the land on earth, if you were to dig a tunnel through the center of the planet, would you end your tunnel on the land? My calculations have ranged from about 20% to 40%. I know there are weaknesses in my method that I haven't accounted for and I'd like a more authoritative number.
- Not Planning Anything, No Sir.
Well, this shoots all of my childhood "dig a tunnel to China" plans right to heck, now doesn't it? Unless I start in Chile, I guess...
Actually, your estimate, low as it may seem, is way too high. By an order of magnitude, on the upper end. According S.K. Runcorn in Continental Drift (quoted in "Antipodal Location of Continents and Oceans," Rory Thompson (April 1967). Science, 156, 263-264)(Since it's such a fancy bona fide scholarly source, I thought I'd put the whole citation), "only 4 percent of the area of the continent is antipodal to continent." For a visual representation of that, check out the Wikipedia article's illustration. I'm amazed by this seemingly stunningly low number.
If whatever project you're not planning is supposed to originate in the States, good luck. The entire lower 48 are about as completely lacking in antipodes as you can get. For instance, a tunnel begun here in Provo would put you right in the southern Indian Ocean, about the latitude of New Zealand. For more non-devious-planning fun, check out this site. It's seriously awesome.